The present invention relates generally to barcode scanners, and, more specifically, to dynamically balancing spinners thereof.
A typical barcode scanner reflects a laser beam from a multi-faceted spinner having mirrors which reflect the laser beam toward cooperating pattern mirrors for producing a pattern of scanning lines which are reflected off a conventional barcode attached to a consumer product, for example. The light reflected from the barcode returns through a collection optical system within the barcode scanner wherein it is conventionally decoded for obtaining the corresponding information associated with the scanned item.
Hand-held and relatively simple barcode scanners use a slowly rotating spinner for which the dynamic balance thereof is insignificant. However, other barcode scanners require relatively fast scanning speed, and therefore operate the spinners at higher rotational speeds, which therefore must be dynamically balanced for obtaining smooth operation. The spinner mirrors are relatively large and may be rotated at speeds up to about 8,000 rpm typically requiring dynamic balancing in two axially spaced apart planes.
Dynamic balancing is a conventional process in which a rotor is mounted atop a balancing machine and rotated at a given operating speed. The rotor typically includes two predefined balancing planes, with the balancing machine measuring unbalance thereat and displaying suitable corrections therefor. A balance correction may include the addition or removal of a specific amount of mass, at a specific radius from the centerline of rotation, and at a specific angular position about the rotor in each of the two planes.
In the example of the barcode spinner, the removal of weight at the balance planes is impractical in view of the fragile nature of the spinner rotor. Accordingly, balance correction is typically effected by bonding a lead tape at the required position, or by applying a weighted adhesive in the exemplary form of a hot melt.
In either example, the amount of balance correction is subject to inaccuracy in manually providing the required amount of mass at the correct radial and angular positions. The balanced rotor may be retested to determine the acceptability of the correction, and re-balancing may be required if the originally corrected balance is not within acceptable limits. This process requires trial and error which decreases the efficiency of the process.
Accordingly, it is desired to provide a new system and method for balancing rotors, such as barcode scanner spinners, which reduce or eliminate the need for trial and error balancing.